The coverage gap is a temporary limit on what most Medicare plans cover for prescription drugs, according to Medicare.gov. It is also known as the donut hole, and not everyone reaches it.
The coverage gap in 2015 begins once a member receives $2,960 of coverage. In 2016, the limit increases to $3,310, and it may change every year, states Medicare.gov. People who are under the Extra Help Medicare plan do not enter the coverage gap. Once a member reaches the coverage cap, he pays 45 percent of the cost of drugs. A Medicare patient can get discounts if he gets drugs from a pharmacy or orders drugs via mail.